/*
 * Copyright 1999-2012 Alibaba Group.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
/**
 * (created at 2011-1-22)
 */
package fm.liu.timo.parser.ast.expression.primary;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import fm.liu.timo.parser.ast.expression.Expression;
import fm.liu.timo.parser.visitor.Visitor;

/**
 * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
 */
public class MatchExpression extends PrimaryExpression {
    public static enum Modifier {
        /** no modifier */
        _DEFAULT, IN_BOOLEAN_MODE, IN_NATURAL_LANGUAGE_MODE, IN_NATURAL_LANGUAGE_MODE_WITH_QUERY_EXPANSION, WITH_QUERY_EXPANSION
    }

    private final List<Expression> columns;
    private final Expression       pattern;
    private final Modifier         modifier;

    /**
     * @param modifier never null
     */
    public MatchExpression(List<Expression> columns, Expression pattern, Modifier modifier) {
        if (columns == null || columns.isEmpty()) {
            this.columns = Collections.emptyList();
        } else if (columns instanceof ArrayList) {
            this.columns = columns;
        } else {
            this.columns = new ArrayList<Expression>(columns);
        }
        this.pattern = pattern;
        this.modifier = modifier;
    }

    public List<Expression> getColumns() {
        return columns;
    }

    public Expression getPattern() {
        return pattern;
    }

    public Modifier getModifier() {
        return modifier;
    }

    @Override
    public void accept(Visitor visitor) {
        visitor.visit(this);
    }
}
